In filthy weather I travel submerged at slow ahead; my submerged time is limited by air, not battery power. I then surface, run at 1/3 ahead to recharge, then repeat, rinse, etc until the weather clears up. It also helps if you upgrade to the newer batteries as they become available. By running at faster speeds you deplete your batteries faster, which means you have to spend more time surfaced to recharge and are thus deaf for longer periods and could potentially miss contacts. By leaving your battery until 25% left you put yourself in a position wherein you could potentially run out of power if hunted or you have to run at high speed submerged for some time to pursue a fast target. A couple of times I have nearly completely drained my battery keeping up with a fast freighter in filthy weather. I was able to finish the hunt because I started it with a full or nearly full battery.
__________________
|